2. State Parks around Gunnison for 5 days
3 State Parks round Pueblo for 5 days.
Also I would appreciate any advice about towing across Route 50 and just how tricky it might be to get up and over Monarch Pass.
As already reported there are no state parks around Gunnison. We stay regularly in Gunnison at the Tall Texan RV Park which is on the road out toward Crested Butte. We much prefer that to the area around Blue Mesa Lake, but that is our personal preferance. There are some really nice National Forest campgrounds around Almont, between Gunnison and Crested Butte.
Just another personal opinion: I would bypass Pueblo altogether. But you may have personal reason to stay there.
I'd take CO 115 near Canyon City and head on up to Colorado Springs. One of the nicest state parks anywhere in the country is Cheyenne Mountain. Of course, reservations must be made long in advance to get a site there.
As for Monarch, we've been over it so many times we feel entirely secure about it. As has already been reported there are many places where it is two-lane uphill so you can just drive you own pace and let others pass. Down hill--just keep it in a low gear and keep it slow; don't worry about the traffic.
The Salida/Buena Vista area is a really nice area and there are many good RV parks around Buena Vista. Unless you really have a reason to stay in Pueblo you might stop over at Buena Vista before going on up to Colorado Springs.